Preheat oven to 350 degrees F. Spray inside of a loaf pan with non stick spray, or better yet line it with parchment paper so it is easier to lift out when done.
In a bowl blend together can of pumpkin puree with spice cake mix dry mix. Make sure all dry bits are incorporated. If you want to add crushed nuts or chocolate chips use 3/4 of a cup, fold that in.
Pour batter into pan and smooth out so it is the same thickness all the way across and bakes evenly. Bake for 35-40 or just until toothpick comes out mostly clean with moist crumbs attached, check often beyond 35 minutes as you want it to not overbake and dry out.
When done run a knife along edges to make sure it is not stuck to lift out, or lift out with parchment paper. Set gently on a cooling rack to cool before slicing. If you leave it in the pan it will continue baking and become more dry.